The present invention relates to a clamp assembly for clamping the outer surface of a tubular object, such as a pole. In particular, the clamp assembly of the present invention finds use in clamping the outer surface of one or more poles of a pole assembly.
Pole assemblies comprising a plurality of individual poles attached or connected end to end are known in the art. In general, known pole assemblies may be divided into two categories: telescopic pole assemblies, in which a first pole extends at least partially within a second pole; and modular pole assemblies, in which first and second poles are connected at their ends.
A telescopic pole assembly typically comprises a plurality of poles that may be moved between an extended position and a retracted position. The poles are provided with a range of different nominal diameters. The diameters of the poles are selected such that a given pole may extend partially or wholly within one or more poles of a larger nominal diameter and/or have one or more poles of a smaller nominal diameter extend partially or wholly therewithin. In this way, the plurality of poles may be arranged to move between the retracted and extended positions in a telescopic manner. The poles of the assembly are extended telescopically to form a pole assembly of the required length.
Similarly, modular pole assemblies comprise a plurality of individual poles. However, unlike telescopic pole assemblies, the poles are not nested and extendable in a telescopic manner. Rather, the pole assembly is constructed by connecting individual poles in an end to end configuration. A plurality of poles are connected in this manner until the pole assembly is of the required length.
Both types of pole assembly generally comprise means for locking adjacent or nested poles to achieve the required length. These means include clamps, screw-fitting connections, push-fitting connections and other locking devices. As noted above, the present invention relates to clamp assemblies, more particularly quick release clamp assemblies for attaching poles of a pole assembly, in particular a telescopic pole assembly.
Clamps known in the art and used to secure tubular objects generally function by applying a radially compressive force to the outer surface of the tubular object. Quick release clamps function in the same way, whilst incorporating means for enabling the user to engage and disengage the clamp as quickly and as effortlessly as possible. For example, the clamp may be tightened or released by the movement of a single arm or lever. Various quick release clamping mechanisms are known and are commercially available.
A common clamping mechanism is disclosed in CA 2428916. This patent relates to a quick release assembly for securing a sleeve about a tubular structure where the sleeve has first and second outwardly projecting lugs that may be drawn together toward one another to compress the sleeve. Each one of the lugs has a bore extending therethrough and is positioned on the sleeve such that the bores are generally aligned with one another. The bore on the first lug is internally threaded. The clamping mechanism comprises an elongate bolt member receivable through the bores in the lugs. The bolt member has a first threaded end that threadably engages the threaded bore through the first lug. The clamping mechanism further comprises a tensioning member operable between an engaged and disengaged position. When in its engaged position, the tensioning member bears against the second lug and draws the first lug toward the second lug to compress the sleeve. When in its disengaged position the tensioning member releases the force drawing the first lug toward the second lug. The amount of compressive force applied by the tensioning member is adjustable through threading the first end of the bolt member into or out of the threaded bore in the first lug.
US 2002007538 discloses an alternative quick release clamping mechanism, wherein a hollow cap member is pivotably attached to a base member, both comprising a resiliently deformable block of cushioning material which can be removably inserted. In the open position, the hollow cap member may be selectively pivoted away from the base member. In the closed position, the hollow cap member is pivoted towards the base member and the elongate object is releasably received by and between the base member and the hollow cap member. In the closed position, the resiliently deformable block of cushioning material resiliently embraces and cushions the elongate object. The amount of compressive force applied is fixed and can only be altered by changing the resilient deformable block of cushioning material.
US 2011/0162173 discloses a quick release clamp for a generally cylindrical bar or pipe, comprising a first barrel half and second barrel half. A hinge pin pivotably couples a first edge of the first barrel half with a third edge of the second barrel half. A spring imposes a set force on the barrel halves to bias a second edge of the first barrel half away from a fourth edge of the first barrel half to create a gap, placing the clamp in an open position. A handle includes a base that abuts an outer surface of both barrel halves to compel the second edge of the first barrel half toward the fourth edge of the second barrel half to close the gap, placing the clamp in the closed position. The spring in this case imposes a constant force against the first and second barrel halves.
GB 2171444 relates to a clamp for telescopic tubes, the clamp comprising a spring housing mounted on the outer tube, a resilient member helically wound around the inner tube and secured at one end to a ring rotatably journalled on the housing and a lock means for moving the ring from an unlocked position, wherein the spring is relaxed around the inner tube to a locked position, wherein the spring is caused to grip the inner tube and prevent relative movement between the two tubes.
As highlighted above, a variety of quick release clamp assemblies are known. However, they are all limited in that in the fully closed position, the user is unable to easily increase the amount of compressive force applied to grip poles having a reduced diameter. If any adjustment is possible, the structure of the clamp assembly must first be adjusted or modified manually by the user. For example, in the clamp of CA 2428916, the compressive force applied is adjusted by changing the position of the bolt member. Alternatively, a different clamp assembly or different components, capable of applying additional compressive force to the outer surface of a pole are required.
Pole assemblies offer the advantage of ease of storage, transportation and use. However, in order to provide such advantages, the poles are typically formed using lightweight materials. Such materials allow the pole assembly to be hand held and manipulated by hand. Suitable materials include metals, including aluminium and aluminium alloys, polymers, including fibre-reinforced polymers, in particular polymers reinforced with carbon fibres.
A longstanding problem associated with using light weight materials however is that the poles wear with time. This is only exacerbated by the use of clamps which, as discussed above, generally function by applying a radially compressive force to the outer surface of the poles. The outer surface of the pole can wear to such an extent that the clamp is no longer able to grip the outer surface sufficiently. In such circumstances, the pole which is worn must either be replaced or an alternative clamp capable of gripping a pole with a smaller outer circumference must be used.
Accordingly, there remains a need for an improved quick release clamp, particularly for use with telescopic pole assemblies, wherein the clamp is able to accommodate changes in the pole outer diameter, for example arising due to wear of the pole.